Plate-girder



H. H. Ronssmf.l

(No Model.)

PLATE GIRDER.

Patented July 9', v1895.

No. 542,283.v

lNVENTEl-R:4

l more or less material difference where a pluv rality of cover-platesare employed. All stress y v PATENT raten'.

HARRY H. ROUSSEAU, OF PITTSBURG, PENNSYLVANIA.

PLATE-cisnes.

SPECIFXCATION forming part et Letters Patent No. 542,283, dated July 9, 1595. Application tiled November 14, 1894. Serial No. 528,721. (No model.)

To all whom it 'may concern.- Be it known that I, HARRY H. ROUSSEAU, a citizen of the United S-tates, residing at Pittsburg, county of Allegheny, andState of Pennsylvauia, hav`e invented certain new and useful Improvements in Plate-Girders, of which the following is a specification.

The invention relates to such improvements; and it consists of the novel construction and combination of parts hereinafter described, and subsequently claimed.

lReference may be had to the accompanying drawings, and the letters of reference marked thereon, which form a part of this specification.

vSimilar letters refer to similar parts in the 'I several figures therein.

ThoughY it is. now understood among the envgineering profession that the truepr eectivc depth of a plate-gilder is the'dept-h or vertil caldistance between rivet-hole centers, by a .curious confusion betweenrolled and' built 'sections, and in accordance with long-established usage, it is still commonly taken as the distance between the centers of gravity of the edge ianges of the girder. I

In ordinary plate-girder construction the edge flanges consist of two angle-'irons riveted to opposite sides of the web along each longitudinal edge. If flan ges ot' greater crosssectional area are required than can be obtained by two angle-,irons along each edge, cover-plates are' added to the angleirons at both top and bottom of the web until the desired area is obtained.v The center of gravity of 'each edge flange is thus moved farther `outward from the line of rivet connection Iwith the web in proportion to the number and thickness of. thecover-plates employed; and it will beiseen that the discrepancy between the true epth of a built-up girder and the depth c nimonly assumed as the basis for callthe flange-section does'not coincide with the vline of rivet connection the consequent transeulatio varies from a diierence that is per- 5' haps negligible in a girderhaving only a single pair of angle-irons along each edge to a exists rst in' the web and is transmitted to the `flanges from the web through the connectingrivets, and when the center of gravity of flan ge.

mission ofstress to the flange eccentrically to its center of gravity causes tiexure in the considered to be osetor compensated for by making the flanges of sufficient dimensions to alone take upall bending stress caused by the load carried by the girder and disregarding the fact that approximately one-sixth'of the Web-area itself is available to resist bending and must resist bending-stress before'deiiection takes place and causes the flanges to begin'to assist the web. lt is thus apparent that the Ordinar)7 methods of computing the necessary dimensions of the flanges of a built-u p girder give more or less inexact results and that the flangeswill in many eases be made of unnecessarily large dimensions to compensate for possible variations and ap- The object of my invention is to produce a plate-girder. whose dimensions can be more accurately determined to meet the given requirements in each case, as well as to cheapen This ilexure is not calculated, but is and facilitate the construction and use of such a girder. By'distributing the mass of flange metal symmetrically about the line of rivet connection with the web, as shown in the drawings, I can produce a girder approximately free from the objectionable features n above set forth and which has many structural .advantages 'over the built-up girders heretofore in use. l

Figure l of the drawings. is ya view in isometrical perspective of my improved plategirder. Figs. 2,3, and 4 are cross-sectional views-illstrating variousfeatures ot' my invention.

A represents the web-plate, its top and bottom with longitudinal edge flanges. The flanges, as shown in Fig. l, are made up. wholly of angle-irons B, secured along the edges of the web by rivets B" inserted through the web andthe lapping v ertical legs of the angle-irons, the vhorizontal legs of which project in parallel planes from opposite sides of the web along -each edge. There are thus secured along each edge of the web, as shown in Fig. l, fourangle-irons, which together form an'edge iange for the web, I- shaped in cross-section, two of the horizontal legs of the angle-irons being above and two below the line of rivet connection.

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may be formed of straight sections F of aning of the stiffener nor the use of a tillersuoli parts together, is required.

'of my improved girder invarious Ways, as byv gle-irons of each flange should the conditions edge llanges, whatever their cross-sectional The arrangement of the lapping-legs of the' angle-irons may be varied as desired,and I have shown them lapped in different positions in the drawings; but I prefer the arrangement shown in Fig. 1, in which the vertical legs ot' the outer an gle'irons are contiguous to the web-plate An increased cross-sectional area of flange can be secured either throughout or in lpart increasing the size of a part or all Vof the angle-irons, .or by the use of side plates C, secured upon the lappedwlegs of the angle-irons, r by the use of horizontal plates C', riveted to thehorizontal legs of the inner angle-irons.

A cover-plate D maybe used when desired; but ordinarily a sudicient cross-sectional area ofllange'can be secured by the use ofthe auxiliary plates C and C', in Which case I prefer to dispense with the cover-plates, and, if railway-ties are lo rest upon the girder, to project the web-plate a short distance beyond the top-flange to form a tongue A', adapted to enter a cross-groove in the superimposed tie to prevent longitudinal movement of the tie transversely of the girder. The tongue may be dispensed with when so desired.

The connecting-plates for lateral bracing, in constructions where my improved girder is employed, can be attached to the horizontal leg of the inner angle-iron of the top ange, as shown at E, whereby, in the absence of a cover-plate, I am able to wholly dispense with projecting rivet-heads above the girder, permitting the ties or other supported parts tol rest directly upon the flange of the girder without countersinking the rivet-heads or nolching the ties to receive the rivet-heads, as commonly practiced.

When vertical stit'feners are required, they gle-ron, each having one leg riveted directly to the web-plate and its ends bearing, respectively, upon the horizontal legs of the inner angle-irons of the opposite flanges. The ends of the stlfenejrs fit squarely into the angles formed by the horizontal legs of the inner angle-irons and the web-plate, and neither crimpplate, as now commonly practiced in fitting Shorter stilfeners F may be inserted between the parallel horizontallegs of the auof loading render them desirable. Y

In calculatingthe dimensions of a girder of my improved construction te meet given requirements the true depth or distancebetween rivet-hole centers is approximately the distance between the centers of gravity of'the area, and may, with all practicable accuracy,

` be made the basis otcalculation, and the center of gravity of the flange-section beingapprogimately in'fthe line of rivet connection `with the web flexnre is avoided in transmitting stress'to theange. The engineer being thus enabled to' easily calculate .with com- Vparativeaccuracy the necessary dimensions,

' allowed for and the edge flanges made correspondingly smaller, resulting in ec'onorny in the manufacture ofthe girder. g t

My improved construction requires fewer' rivets and less skilled labor than construe tions heretofore used, resultingin a consider-4 able saving in the cost of the girder.l l.

What I claim as new, and desire to secure by Letters Patent, isv

I1. A plate-inet l girder comprising,r a flat web-plate and bui t-u p edge-flanges severally composed ot a plurality of connected irons having their combined mass distributed symmetrically'about the line of rivet-connection withthe web, substantially as described.

2. In spiate-metal girder, the combination witha flat Web-plate, of an edge-flange formed of separate angle-irons onopposite sides of the web, and liangeattaching rivets severally inserted,perpendicularly through thel web, and the irons on both sides of the web, approximately at the center of-gravity o t the flange-section, substantially as described.

3. In a plate-girder, the combination with a web-plate of an attached edge-flange coinprisidg `four angle-ironsiarranged in pairs on opposite sides'of the web with' lapping verti- Y cal legs and their horizontal legs projectingr in parallel planes, and attaching rivets severally inserted through the web and the lapping legs of the fou r angle-irons, substantially as described; I l

4. In a plate-girder, the combination with a .web-plate and I-shaped flanges secured to its opposite edges, of stilening platesseverally Vcomprising a straight section of angleiron secured by one of its legs directly to the web-plate and bearing at opposite ends upon the inner edges of the I-shaped flanges, substantially as described.v

5. A plate-metal girder comprising a web having I-shaped flanges en its opposite longitudinal edges and its center-line coincident with thecenter-lines of the web-portions ot the respective flan'ges, substantially as described. p Y

In testimony Whereotl have`herennto set my hand this 5th day of November, 189i.

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